1. Field of the Invention
The present invention relates to a head-mounted image display device for displaying images on a screen showing a virtual space and to a data processing apparatus including this device.
2. Description of the Prior Art
The design of electronic circuits or experiment thereon requires materials such as data sheets due to the need to confirm the specifications of parts to be used. In this case, the materials are scattered on and around the designer's desk, thereby limiting the working space or hindering the designer from finding required materials quickly. This reduces the working efficiency.
To carry out design efficiently, computer aided engineering (CAE) for working out designs using computers has been introduced. That is, a paperless design environment has been established in which, for example, materials such as data sheets are registered in a computer to enable them to be displayed and referenced on the screen of the display as required. The above inconveniences have thus partly been eliminated.
If, however, a large number of parts are to be used and a large number of materials must be referenced at the same time, although several windows can be opened on the screen to display different materials in the different windows, the windows must sometimes overlap each other if a large number of windows must be used simultaneously due to the physically limited size and resolution of the CRT display for displaying information. As a result, the amount of information that can be referenced at the same time is limited, and the efficiency provided by the introduction of CAE is thus limited; in some cases, it is faster to find required materials among those scattered on and around the table as described above.
The working efficiency is also reduced in the maintenance or repair of an installed apparatus, wherein the operator must carry out such an operation while referencing instruction manuals and wherein because the surroundings are in disorder, the operator cannot place the manuals in positions in which they can be referenced appropriately. Under such conditions, however, it is further difficult to place a CRT display close to the operator, and the introduction of CAE is impossible. Thus, no other appropriate solutions were available.
Several methods of mounting a display apparatus on the operator's head and displaying information from materials thereon have thus been proposed.
Published Unexamined Patent Application No. 5-100192 describes a method of displaying screens from electronics such as word processors on a spectacle-like display, but this is only a spectacle-shaped variation of conventional displays and is not suited to the presentation of a large number of materials. Published Unexamined Patent Application No. 4-263283 proposes a portable virtual reality apparatus, but this simply provides an artificial reality apparatus and is not suited to the manipulation of displayed data.
In addition, for conventional head-mounted image display devices, several problems arising from the need to alternatively view a virtual image on the liquid crystal display and the corresponding image on the external keyboard due to the large difference in image quality between these images, have been pointed out. To solve this problem, some conventional techniques cause a display image and the corresponding external image to overlap each other. Head-mounted image display devices of this type, however, also have problems. For example, in such apparatuses, the visibility is very bad because external images are simply caused to overlap the corresponding display images, and alternatively viewing different images may strain the operator's eyes.
In addition, in head-mounted image display devices, when, four example, data is input to a word processor, keys to be pressed must be confirmed while viewing a display image, so the external keyboard must be checked while watching the display image.
To solve this problem, a means for switching between an external image and the corresponding image from an arithmetic operational device may be provided, or a configuration that enables the use of part of the field of view for watching the display while using the other part for checking the exterior may be provided, as proposed in Published Unexamined Patent Application No. 5-100192. In this case, however, since data must be input while using a particular part of the field of view to check the input device, mounting the image display device on the operator's head eliminates the freedom of the operator's inputting position, and long time work thus results in a significant fatigue. In addition, if a keyboard is used as an input device, the input operation is very difficult when the keys are larger than the tips of the operator's fingers, so the limit of the practical size of portable terminals depends on the size of the keyboard. Furthermore, due to the fixed arrangement of keys in conventional keyboards, optimal key arrangements for various applications are not available. In this information-oriented society, more and more attention is being paid to multimedia applications, so people must often deal with data in which motion and still pictures are mixed. Under these circumstances, the need of complicated procedures for creating motion pictures hinders people without expertise from providing adequate expressions using multiple media effectively. For hypermedia applications, HyperCard commercially available from Apple Co., Ltd is popular, but requires a large number of mouse clicks, thereby possibly resulting in mistakes in clicking positions.
For movie postproduction processes for processing, synthesizing, and editing movie materials, a large amount of time is required to complete the process due to the need to accurately carry out complex procedures according to pre-calculations, and the flexibility of these processes is limited; it is impossible to test various combinations of images during the process.
In addition, if a head-mounted image display device is used, only the person wearing the device can view image display information output from a data processing apparatus. If a plurality of people have to view image display information output from the data processing apparatus, then:    (1) these people must use a single head-mounted image display device in turn, or    (2) another data processing apparatus with a CRT display must be provided.
In this manner, a plurality of devices may be required according to a particular purpose and usage.
Attempts are being made to reduce the size of computers and word processors, and the utilization of portable data processing apparatuses is increasing. Such portable data processing apparatuses ordinarily include an open type display that is opened in use. However, with the further reduction of the size of portable data processing apparatuses, the extension of the range within which such devices can be used, and the increase in demand for functions of publicly creating confidential documents, the use of head-mounted image display devices has been proposed. As in Published Unexamined Patent Application No. 5-100192, such apparatuses comprise an arithmetic processing device and a head-mounted image display device to display screen information output from the arithmetic operation device, through the head-mounted image display device as enlarged virtual images. In such conventional structures, the arithmetic operation device and the head-mounted image display device are always separated from each other, they must be carried separately, resulting in poor portability despite their reduced sizes. Even if the head-mounted image display device is carried in an outer sheath case, handling becomes cumbersome, and faults are likely to occur.